The present invention is generally related to two piece can making equipment, and more specifically related to an air manifold for can making equipment, and a necking machine incorporating the air manifold.
Static die necking is a process whereby the open ends of can bodies are provided with a neck of reduced diameter utilizing a necking tool having reciprocating concentric necking die and pilot assemblies that are mounted within a rotating necking turret and movable longitudinally under the action of a cam follower bracket to which the necking die assembly is mounted. The cam follower bracket thereby rotates with the turret while engaging a cam rail mounted adjacent and longitudinally spaced from the rear face of the necking turret. A can body is maintained in concentric alignment with the open end thereof facing the necking tool of the concentric die and pilot assemblies for rotation therewith. The reciprocating pilot assembly is spring loaded forwardly from the reciprocating die member. The forward portions of the die member and pilot assembly are intended to enter the open end of the can body to form the neck of the can.
More specifically, the die member is driven forwardly and, through its spring loaded interconnection with the pilot assembly, drives the pilot assembly forwardly toward the open end of the can. The outer end of the pilot assembly enters the open end of the can in advance of the die member to provide an anvil surface against which the die can work. The forward advance of the pilot assembly is stopped by the engagement of a homing surface on the necking turret with an outwardly projecting rear portion of the pilot assembly, slightly before the forward portion of the die member engages the open end of the can. As the die member continues to be driven forwardly by the cam, its die forming surface deforms the open end of the can against the anvil surface of the pilot assembly to provide a necked-in end to the can body.
A necking machine of the type discussed above is disclosed, for example, in U.S. Pat. Nos. 4,457,158 and 4,693,108. In the U.S. Pat. 4,693,108, each necking station also has a container pressurizing means in the form of an annular chamber formed in the pilot assembly. The container pressurizing means acts as a holding chamber prior to transmitting the pressurized fluid into the container from a large central reservoir located in the necking turret. In the type of static die necking discussed above to which the present invention pertains, pressurized fluid internally of the container is critical to strengthen the column load force of the side wall of the container during the necking process. There are particular problems inherent in introducing sufficient pressurized fluid into the container as the speed of production is increased. Further, the cost of pressurized air has risen to be a significant percentage of the cost of manufacturing.
A necking machine addressing these problems is disclosed in PCT/US97/05635. This necking machine includes a manifold, illustrated schematically in FIG. 1, adapted to supply air at different pressures to the can. Specifically, the manifold includes ports which supply low, medium and high pressure air to the can. The manifold also includes low, medium and high pressure bleed ports which recycle air from the formed can back to succeeding cans to be formed. By recycling air, this design reduces the total amount of air necessary in the forming process. Although this necking machine represents an improvement over earlier necking machines, the use of three distinct pressure supplies and three recycle streams results in a much more complicated necking machine.
Therefore, it would be advantageous to have a relatively simple manifold, necking machine, and method of necking a can which supplies sufficient air to maintain the can under pressure while necking, yet requires less air than conventional devices and methods.
Briefly, in one embodiment, the present invention includes an air manifold adapted for use in a can necking module comprising at least one port adapted to supply low pressure air to a can prior to necking, at least one port adapted to supply high pressure air to a can prior to necking, at least one port adapted for bleeding high pressure air from a can after necking, at least one port adapted for bleeding low pressure air from a can after necking and not having ports adapted to supply or bleed air at pressures intermediate between the high and low pressures.
The present invention also includes a necking module comprising an air manifold having at least one port adapted to supply low pressure air to a can prior to necking, at least one port adapted to supply high pressure air to a can prior to necking, at least one port adapted for bleeding high pressure air from a can after necking, at least one port adapted for bleeding low pressure air from a can after necking and not having ports adapted to supply or bleed air at pressures intermediate between the high and low pressures, a necking die and a rotor.
In addition, the present invention includes an air distribution system for can necking comprising an air compressor, a high pressure line, a low pressure line; and a least one necking module having an air manifold including at least one port adapted to supply low pressure air to a can prior to necking, at least one port adapted to supply high pressure air to a can prior to necking, at least one port adapted for bleeding high pressure air from a can after necking, at least one port adapted for bleeding low pressure air from a can after necking and not having ports adapted to supply or bleed air at pressures intermediate between the high and low pressures.
The present invention also includes a method of necking a can comprising the steps of supplying a first can to a necking module including an air manifold having ports adapted for low pressure air, ports adapted for high pressure air and not having ports at pressures intermediate between the high and low pressures, charging a first can with low pressure bleed air through a first reuse port, charging the first can with high pressure bleed air through a second reuse port, charging the first can with high pressure air from a compressor through at least one feed port, inserting the first can into a necking die, necking the first can, bleeding high pressure air from the first can to at least one succeeding can through a first regen port and bleeding low pressure air from the first can to at least one succeeding can through a second regen port.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed.